Mining Asteroids
The scarcity of the precious metals is not really that there are
not lots of them on Earth, it is just that over 4 billion years of
tectonic mixing they have mostly moved to Earth's core.
What little is near the surface
is hard to find and therefore
expensive (like $10,000 per pound for platinum).
These same metals are not hidden on asteroids, since there has been
no tectonic action and almost no gravity.
There is
more precious metals in one asteroid than we could every hope to mine from all the crust of the Earth.
Getting There
In the past it has been too expensive to get to an asteroid and then bring back the metal.
But it seems this is about to change.
Space Tethers should reduce costs
of getting to Low Earth Orbit (LEO) to under $100 per lb.
From LEO we need about a 5 km/sec delta-V.
This same tether can also toss the payload toward the Moon,
where it can pick up speed from a
gravity-assist flyby
of the Moon. With the tether and the flyby, there would be less than 1 km/sec
to be made up by
ion drives.
It will take very little fuel to get to the asteroid.
Getting Back
If we are willing to enter the atmosphere, we don't need much delta-V on the way back
because it is downhill. Less than 0.5 km/sec for some Near Earth Asteroids.
We could have a small tether on the asteroid that provided that delta-V.
If we don't want to enter the atmosphere fast, we could reverse the outbound
process by doing a Lunar flyby to loose energy and then having the LEO tether
catch us. In any case, a small
Space Tug that
is like 1/100th the mass of the return cargo should be enough.
These space tugs can go back for another cargo after they bring one in.
On-Earth Market
There is a very clear and very real market for Gold, Platinum, etc.
If you could bring the metals back, you know you could sell them.
If you brought back
more than a few billion dollars worth every year you could impact the price.
However, it seems that the high price of Platinum has made people who would like to
use it bend over backwards to use something else. If the price were to drop many
of these would switch to Platinum. Also, if Platinum were cheaper, fuel cells
could compete better against batteries and become a very large market. So it
seems the price would not drop all that much even with a big increase in supply.
Off-Earth Market
If it costs $2,000/lb to get materials to orbit, then anything in orbit is valued
at at least $2,000/lb. If someone was building a space-hotel or orbiting-farm
they would be happy to get iron, aluminum, water, carbon, etc. for less than this.
So mining asteroids for this looks good. However, if
Space Tethers can reduce the cost to $100/lb
and eventually even $20/lb, it becomes harder to make a profit on simple
materials for LEO.
Economics
Some studies indicate that asteroid mining equipment could produce 100 times its own
mass in mined metals every year. An ion-drive rocket should be able to
return 20 to 100 times its mass in metals each trip.
With Platinum being
100 times our launch cost per pound ($10,000/lb vs $100/lb), these numbers
seem to indicate it would be very profitable.
Financing Asteroid Mining
A mining company could decide to mine asteroids if they thought it was
a reasonable investment.
It is not that far off, probably 5 to 15 years. Most people
reading this probably think that is optimistic, but it could be that
most people are too pessimistic about space development these days.
Asteroids on Moon
The surface of the moon does not have active tectonic plates to mix in asteroids
that fall on it. So for billions of years it has been collecting asteroids.
They usually vaporize on impact and mix in with the regolith, which may be
like 0.5% asteroids at this point. So mining the regolith of the moon might
be a good way to get asteroids.
Links
Contact
Send email to vince@offshore.ai.
Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets
by John S. Lewis